In wireless, radio communications, many transceiver products are available which package a radio antenna along with the electronics necessary for its operation to provide convenient wireless, radio communications capabilities. For several reasons, such products are often subject to conflicting size requirements. For example, wireless transceivers for use with cellular telephones or personal computing devices must be conveniently sized for portability and user experience. However, depending on the radio operating frequencies and required signal strengths involved, the products must exceed a certain minimum size in order to accommodate a radio antenna of appropriate physical dimensions.
The limitations of conventional wireless transceiver products can be illustrated with particular respect to current wireless adapter systems, which provide plug-in wireless communications capabilities to a host system such as a laptop computer. Common wireless adapters of this type may operate for example similarly to a cellular telephone or wireless network adapter, having a wired data port for connection to a host system at one end and including a radio transceiver. Such wireless adapters can therefore be considered to include three distinct parts, a data port, an intermediate electronics package, and an antenna.
For example, a wireless adapter of this type can be connected to provide wireless capabilities to a host computer through a standard interface such as a PCI, PCMCIA, Express, Firewire or USB interface. In the case of PCI, PCMCIA and Express Card interfaces, the adapter electronics section is typically located or enclosed substantially within a slot of the host system, and the antennas are located on a portion of the adapter external to the slot. In the case of a USB interface, the adapter electronics and antenna are typically both contained in a package external to the host system since the USB interface is only a relatively small connection port. The wireless adapter can also comprise one or more movable antenna portions which can increase design flexibility, but such systems are still constrained by limitations such as described below.
A problem with the above design is that the radio antenna structure must be more or less completely contained within the wireless transceiver package. In the case of a monopole antenna, an antenna body within the package, such as a patch antenna, a whip or stubby antenna, or a planar inverted F antenna (PIFA), is radiated against a ground plane also contained within the package, for example the electronics ground plane connected through the data port to a host device. For example, United States Patent Application Publication Nos. 2007/0035452 and 2007/0044145 both describe a USB wireless adapter having an antenna radiating against an internal ground plane. In the case of a dipole antenna, two antenna bodies contained in the package radiate in combination. In each case, the dimensions of the antenna bodies and the effective antenna length are limited by the dimensions of the wireless transceiver package. Furthermore, the effective bandwidth of antennas constructed in this manner may be limited.
Another particular constraint in the design of wireless communications packages comprising both electronics and radiating antenna bodies is that grounded and/or shielded components are often required, both to facilitate operation of the electronics, and to provide isolation between the electronic components and the antenna. However, such grounded components can also operate for example as de-tuning and de-sensing elements for the antenna, thereby compromising antenna operation.
Another challenge for radio communications systems is in simultaneously satisfying demands for increased data transfer rates, smaller and more inexpensive systems, and increased complexity.
Therefore there is a need for a wireless communications system for coupling with an external system, such as a wireless adapter, that is not subject to one or more of the limitations of the prior art.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.